1. Technical Field
This disclosure relates to an image forming apparatus, and more specifically to an image forming apparatus including a recording head for ejecting recording liquid and a method of discharging the recording liquid from the recording head.
2. Description of the Related Art
Image forming apparatuses are widely used as printers, facsimile machines, copiers, plotters, or multi-functional devices having two or more of the foregoing capabilities. Such image forming apparatuses may have a recording head to eject recording liquid (e.g., ink) onto a recording medium (e.g., a sheet of paper) to form an image on the recording medium. The recording head is also referred to as, e.g., droplet ejection head, liquid ejection head, recording head, ink ejection head, or inkjet head.
In such an image forming apparatus, bubbles may enter nozzles of the recording head and reduce the ejection performance of the recording head. Hence, to recover the ejection performance, a conventional art is known to bring a cap into contact with a nozzle face of the recording head (also referred to as a recording-liquid ejection face, i.e., a face from which recording liquid is ejected) and suck the recording liquid from the recording head to discharge the bubbles from the nozzles (head sucking).
The above-described head suction is not problematic for an image forming apparatus having a recording head oriented vertically downward (so as to eject recording liquid vertically downward). However, the head suction causes the following problem in an image forming apparatus having a recording head oriented vertically upward (so as to eject recording liquid vertically upward).
For example, in a case where the above-described head suction is employed in an inkjet-type image forming apparatus having a recording head oriented vertically upward, a process from when the cap contacts the nozzle face of the recording head to when the pump sucks the recording liquid is not problematic. However, when the cap is decapped (detached) from the nozzle face after the head suction, residual ink in the cap may remain on the nozzle face since the head is oriented upward. Such ink remaining on the nozzle face may firmly adhere on the nozzle face or drip from the nozzle face to a side face of the head and solidify at the side face. As a result, ejection failure may occur in the nozzles or firmly-adhered ink may contaminate a recording face of a sheet of paper.
In this regard, for example, JP-2005-119214 proposes to clean a nipping portion of the cap by a cleaning member. When the cap moves to the capping position, the cap passes an opening of the cleaning member to remove residual ink on the nipping portion. Such a configuration can remove residual ink remaining on the nipping portion of the cap. However, in a case in which head suction is performed on a recording head oriented upward in an image forming apparatus, residual ink remaining in the cap during decapping the cap after head suction may remain on the nozzle face of the recording head.